Patent GB-1182684-A (GB)
Title: Electrostatic Printer
IPC: B65H23/14
Filed: 1967-03-13
Abstract: 1,182,684. Selective printers. RANK XEROX Ltd. 13 March, 1967 [17 March, 1966], No. 11582/67. Heading B6F. [Also in Division G2] Electrostatic printers; electric input arrangements; type-wheel machines; machines coupled for simultaneous operation; multiple type surface selection.-An electrostatic printer 11, Fig. 1, comprises two drawers 19 each of which is provided on its base with a printing unit 12, 13 including a lower assembly supported on standards 28 and a pivotal upper assembly 24 mounted on pivot pins 26, the lower assembly supporting a record web 37, Fig. 4, which is supplied from a roll 38 and passed over a continuously rotating alphanumeric carrier 40, which in conjunction with backing electrodes 42 mounted on a pivotal bar 43 produces a line of latent images, where upon the bar 43 is raised by a bail 106 which is actuated by a solenoid 111 for the record web 37 to be advanced by one line-space. The latent images on the record web 37 are produced by the carriers 40 and backing electrodes 42 in response to application of recording pulses to the backing electrodes 42. Type-band machines.-The rotary carrier 40, Fig. 4, may be replaced by an endless band 113, (Fig. 7). Web feeding, guiding and tensioning arrangements; line-spacing arrangements.-The recording web 37, Fig. 4, is drawn off a roll 38 mounted on flanged portions (51, 52, Fig. 3) of shafts 53, 54 which are journalled in uprights 56, 57, Fig. 2. The web 37 is then passed under a tensioning roller 64 mounted on a bracket 62 which is biased downwardly by a spring 66, the web being then guided over rollers 78, 81 past the printing, developing and fusing stations 39, 44, 47, respectively, to the feed rollers 48, 49, of which the roller 48 is attached to a crank 82, Fig. 2. The crank 82 is articulated to the armature 87 of a solenoid 86 so as to impart a uni-directional displacement to the roller 48 in line-spacing increments in response to actuation of a uni-directional clutch 89. The stroke of the armature 87 is delimited by brackets 92, 93. The successive incremental displacements of the record web 37 raise the arm 62 which carries the tensioning roller 64, in consequence of which a rubber brake shoe pad 71 mounted on a brake lever 69, which is journalled on the arm 62 is raised to release the web roll 38 for rotation and dispensing of a length of the record web 37, whereupon the arm 62 which is biased by the spring 66 re-applies the brake shoe pad 71 to stop the rotation of the web roll 38. The downward pivotal movement of the arm 62 is arrested by a stop 72 which is disposed on the upright 56. Power assisted type actions.-Both alphanumeric carriers 40, Fig. 4, are driven by a common drive motor (172, Fig. 5), through a respective one of a pair of vertically spaced clutch couplings 163 and in association with a timing toothed belt 177 and timing disc 169, which is provided with slots representative of the disposition of the characters on the carriers. The clutch couplings 163 are provided with a respective aperture 167 for the reception of a coupling pin 164 so that the carriers are driven in synchronism when one of the drawers 19, which was withdrawn, has been re-engaged with the drive. Locking devices.-A feeler arm 78, Fig. 4, of a micro-switch 77 bears against the record web 37 to actuate the micro-switch on detection of a break in the record web and cause a warning light on a panel 23, Fig. 1, to be switched on, the recording pulse input to be turned off, the record web feed to be stopped and the fuser at 47 to be moved out of contact with the web. An arm 76 of a further micro-switch 74, Fig. 2, which senses continuously the diameter of the record web roll 38 operates a further warning light on the panel 23 to indicate exhaust of the record web 37. Latent image developing and fusing arrangements.-The latent electrostatic images produced on the record web 37, Fig. 4, by the electrostatic printing units 12, 13, Fig. 1, are developed at the developing station 44 including a container 129 in which two counter-currently driven agitator screws 134, 135, apply finely divided, thermoplastics, electroscopic particles to a magnetic brush 46 which is formed by a non-magnetic shield 133 and a pair of bars 132, 139 one of which bars 132 is a magnet and constitutes a brush member for application of the particles to the record web 37. The quality of the developed images is improved by placing a counter electrode 141 on the opposite side of the recording web 37. The electrode 141 is biased at a potential of from 60 to 100v D.C., having the same polarity as the particles applied to the web. The other bar 139 which is contiguous with the bar magnet 132 is made of steel and used to shunt the lower magnetic field and thereby collapse it in order to prevent the particles from adhering to the shield 133, which is driven in synchronism with the agitator screws 134, 136. The developed images are fused in contact with a fuser 47 having a heated surface 152 and a cold surface 153, the latter being pivotable into contact with the record web 37 by a quadrant 144, Fig. 2, which meshes with a pinion 143 on the shaft 142 of the fuser 47, when the pointer is stopped, e.g. by a detected break in the web, to prevent scorching of the web. In another embodiment, the fuser 47 is replaced by a heated platen (156, Fig. 10), which is mounted on a bellcrank (157) operated by a solenoid (161) to bring the platen out of contact with the record web during ontage of the printer.